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Two adjacent sides of a parallelogram AB...

Two adjacent sides of a parallelogram ABCD are given by `vec(AB)=2hati+10hatj+11hatk` and `vec(AD)=-hati+2hatj+2hatk`. The side AD is rotated by an acute angle `alpha` in the plane of the parallelogram so that AD becomes AD'. If AD' make a right angle withe the side AB then the cosine of the angle `alpha` is given by

A

`(8)/(9)`

B

`(sqrt(17))/(9)`

C

`(1)/(9)`

D

`(4sqrt(5))/(9)`

Text Solution

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The correct Answer is:
B
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ML KHANNA-ADDITION AND MULTIPLICATION OF VECTORS -Self Assessment Test (MULTIPLE CHOICE QUESTIONS)
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  2. Let a-i+j and b=2i-k.The point of intersection of the lines r times a=...

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  3. Let a,b, c be three non-coplanar vectors and r be any vector in space ...

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  4. Let a, b, c be unit vectors such that a + b + c = 0 which one of the f...

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  5. Unit vector vecc is inclined at an angle theta to unit vectors ve...

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  6. If hata,hatb,hatc and hatd are unit vectors such that (hata xx hatb). ...

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  7. If vecu, vecv, vecw are non -coplanar vectors and p,q, are real numbe...

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  8. Let ABCD be a parallelogram such that vec A B= vec q , vec A D= vec p...

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  9. Two vectors a and b are not perpendicular and c and d are two vectors ...

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  10. IF a and b are vectors such that | a + b| = sqrt(29) and a xx (2i+3j+4...

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  11. If the vectors a = i-j+2k, b =2i+4j+k and c=lambdai+j+mu k are mutuall...

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  12. Let P ,Q ,R and S be the points on the plane with position vectors ...

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  13. If a=1/sqrt(10)(3i+k)" and "b=1/7(2i+3j-6k), then the value of (2a-b)....

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  14. Two adjacent sides of a parallelogram ABCD are given by vec(AB)=2hati+...

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  15. The vector(s) which is/are coplanar with vectors hat(i)+hat(j)+2hat(k)...

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  16. If the straight lines (x-1)/(2)=(y+1)/(k)=(z)/(2) and (z+1)/(5)=(y+1)/...

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  17. If a, b and c are unit vectors satisfying |a-b|^(2)+|b-c|^(2)+|c-a|^(2...

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  18. Let vec a=- hat i- hat k , vec b=- hat i+ hat ja n d vec c= hat i+2 h...

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  19. If a and b are vectors in space given by a=(hat(i)-2hat(j))/(sqrt(5)) ...

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  20. The vectors vecAB = 3i + 4k and vecAC = 5i -2j + 4k are the sides of a...

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